Method for producing a pile support arrangement

ABSTRACT

A method of producing pile underpinnings and the like in which piles, which fan out downwards, are connected by subsequently injected concrete.

United States Patent 1 Frank [4 1 Dec. 17, 1974 METHOD FOR PRODUCING A PILE SUPPORT ARRANGEMENT I Anton Frank, Kololdstrasse 37, 8000 Munich 83, Germany Filed: Dec. 29, 1972 Appl. No.: 319,398

Inventor:

References Cited UNITED STATES PATENTS 9/1969 Seidenberg 61/50 X FOREIGN PATENTS OR APPLICATIONS 2,013,992 12/1970 Germany ..61/51 1,801,984 4/1970 Germany ..61/51 Primary Examiner-Jacob Shapiro Attorney, Agent, or Firm-Holman & Stern [5 7 ABSTRACT A method of producing pile underpinnings and the like in which piles, which fan out downwards, are connected by subsequently injected concrete.

10 Claims, 8 Drawing Figures PATENTE SE3 1 H974 SHEET 1!]? 8 i W N r4 7 K g 1 4/ -\\\P W M Q? 44%? v n PATENTEU U531 U974 SHEET 3 OF 8 PATENTED DEC 1 7 I974 SHEET 5 OF 8 PATENTED 1 74 SHEET 7 BF 8 METHOD FOR PRODUCING A PILE SUPPORT ARRANGEMENT BACKGROUND OF INVENTION The invention relates to a method for the production of a support arrangement using piles, and more particularly for the production of such an arrangement under existing buildings or building constructions.

SUMMARY OF INVENTION One object of the invention is to increase the load carrying capacity of pile foundations irrespectively of whether it is a question of already pre-existing pile foundations or new pile foundations. In particular in the case of the construction of underground railways or railroads, it is often necessary to carry out excavations of earth immediately adjacent to already existing builings so that adjacent to an already existing building, a gap is produced in the soil. In the case of bored, injected piles, the load carrying capacity of the piles is not sufficient because due to the great length of the latter, their resistance to bending is not sufficient. Furthermore, in the case of such pile foundations, there is the danger of individual piles being overloaded. In accordance with the method of the present invention, the lengthzbending stress ratio of the piles is substantially reduced. Furthermore, it is possible with the invention to combine a large number of piles together to form a pile compound structure so that a certain degree of equalization of forces occurs when the piles are loaded.

In accordance with one aspect, the method of the present invention resides in producing underneath a building to be underpinned and along pre-existing foundations, a number of piles which are partly vertical and partly oblique, by boring into the ground, at least some of the piles being set as an angle to each other so as to fan out in a downward direction, following which between the piles at individually selected positions, cement or mortar material is injected, with the material forming a connection with the soil and then hardening so that hardened nodes are produced which connect the piles at separate positions, the positions of the injected material being so selected that from several piles, which are-connected bynodal points, stiff structures are produced in the form of at least one triangle, such a structure forming a trussed structure and being capable of taking up vertical and oblique forces and transmitting such forces into the ground.

In accordance with the invention, the piles can be so bored and the positions of injection be so selected that in the direction of the foundation or continuous footing stiff, triangular pile structures are produced. The piles can also be bored in such a manner and the positions of injection can be so selected that stiff triangular pile structures are produced in the direction lying transversely with respect to the continuous footings. The two arrangements can, however, also be combined with each other.

For producing a further reinforcement of the pile structure produced in this manner, tension anchors can be bored through the nodal points horizontally or obliquely downwards, with the earth adjacent to the ends of the anchors being consolidated by cement or mortar injection. Instead of individual nodal points, it is also possible to produce continuous footings or strips by cement or mortar injection, such strips having the advantage that they distribute the load resulting from the pressure of the earth or the overlying structure over the piles. Furthermore, the nodal points connected by strips can comprise rear with the extending horizontal or oblique tension anchors and, in this case, it is convenient for the anchors to engage the strips or footings connecting the nodal points.

Particularly strong nodal points or connections can also be achieved, more particularly in the case of soils which are not suitable for injection of material, by driving at least two washing lances in, so that the soil adjacent to the positions of injection is loosened and washed away by at least one lance or is washed out by another washing lance and following this, the cavity resulting is pressed with cement mortar, which then forms hardened nodes without any connection with the soil.

BRIEF DESCRIPTION OF THE DRAWINGS The method in accordance with the invention is explained with reference to the drawings.

FIG. 1 shows a sectional view of a pile support structure with piles arranged in two rows and which are connected by nodes.

FIG. 2 shows a front view of the support structure in accordance with FIG. 1.

FIG. 3 shows a plan view of the support structure shown in FIGS. 1 and 2.

FIG. 4 shows a further pile support arrangement which is produced in accordance with the method according to the invention using piles which are arranged in three rows.

FIG. 5 shows a front view of the pile support arrangement in accordance with FIG. 4.

FIG. 6 shows a plan view of the pile arrangement shown in FIGS. 4 and 5.

FIG. 7 shows with reference to the pile structure in accordance with FIG. 4 the carrying out of a method for the formation of hardened nodal points or nodal connections between piles for the purpose of producing rigid triangular structures consisting of piles.

FIG. 8 shows an individual part of the apparatus shown in FIG. 7.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows in section the lower part of a building 1, which is provided with a foundation 2. Through the foundation 2 piles 3 and 4 are bored, whose arrangement can be seen from FIGS. 2 and 3. These piles are connected by hardened nodal points or nodal connections 7 and 8, whose purpose will be explained later. Reference numeral 5 denotes the bottom of a soil excavation. Reference numeral 6 shows the bottom of the cellar of the pre-existing building 1. On the front side, that is to saY in front of the bored piles 3, a gunite wall 9 is shown, which is produced during the progress of the removal of material to make an excavation 10. The representations of FIGS. 2 and 3 indicate that the piles 3 and 4 are so bored that they make an angle with each other. If now between the piles 3 and 4 nodal points or nodal connections 7 and 8, respectively, are produced by injecting material, it can be seen that two respective piles form two triangles which as such form rigid triangles. Two such triangular structures are shown in broken lines in FIG. 2. This arrangement has the advantage that firstly the length:stress ratio of the individual piles,

for example, between the foundation 2 and the nodal point 7 and between the nodal points or nodal connections 7 and 8, respectively, is substantially shortened and that secondly two piles form structures, which laterally have a considerable rigidity so that the load carrying ability of the pile system is very substantially increased. The representation of FIG. 3 shows from above the respective inclination of the piles 3 and 4 and their arrangement in the foundation 2.

FIG. 4 shows a second embodiment of a pile structure or arrangement, which has been produced in accordance with the method of the invention. The referecne numerals 1, 2, 3, 4, 5, and 6 have the same meaning as in the example shown in FIG. 1. Departing from the embodiment of FIGS. 1 to 3, a third row of piles is provided, consisting of obliquely bored piles 14. Nodes 17 and 18 are so enlarged that they can connect all three rows of piles together at suitable positions. The nodes 17 and 18 have tension anchors 20 and 21 bored through them. These anchors have their ends surrounded by consolidated zones 22 and 23, which are hardened by injection of material.

FIGS. and 6 show the arrangement of the piles 3 and 4 in elevation and in plan view. The piles 3 and 4 are connected by solidified or consolidated zones 17 and 18, the tension anchors and 21 being attached between the pile bundles. FIG. 6 shows additionally the arrangement of the obliquely bored piles 14, with the oblique setting being indicated by arrows. FIG. 5 shows accordingly how, looking from the front, rigid triangular structures are produced, which endow the rod structure in a lateral direction with a substantially greater resistance to slipping and stiffness, while due to the additional arrangement of the bored piles 14 also perpendicular in relation to the pile structure triangular structures are produced, as can be seen from FIG. 4.

FIG. 7 is a sectional view of the pile arrangement in accordance with FIG. 4. The representation shows two washing lances 25 and 26, which are driven through the gunite wall 2 into the earth behind the gunite wall. Reference numerals 27 und 28 denote so-called packers, of which the packer 27 is shown in FIG. 8 on a greater scale as well. The lance 25 serves as a washing lance and the lance 26 serves as a washing back lance. The packer 28 operates as a closure to the rear of the end of the washing lance. The packer 27 limits the sectional surface of the washing lance for the washing material flowing through. Due to this limitation, the washing pressure can be limited to the intermediate space, for example, between the piles 4 and 14. The washing lance 25 comprises an outer tube 31 and an inner tube 32, which serves for the supply of cement mortar or synthetic resin mortar. A rubber connector 33 serving as a cuff or sleeve seal must increase in diameter in order to reach the seal. When the diameter is increased, the packer is locked and at the same time the sealing is carried out. The spreading out of the connector 33 can, for example, be carried out by the outer tube 31 being moved on with respect to the inner tube 32 by means of a setting screw or tightening screw which is not shown. Since the rubber connector 33 is connected with the inner tube 32 and the inner tube remains stationary, the diameter of the rubber connector 33 must be increased. The rear packer 28 consists principally of a rubber sleeve which is pressed against the tube wall and thus produces a fluid-tight joint between it and the tube. This makes it possibleto limit the escape of washing liquid and mortar to a predetermined length of the washing lance 25 and to produce at certain positions a consolidated zone between the piles 3, 4, and 14.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A method of production of a pile support arrangement for underpinning the pre-existing foundation of a building structure and the like, comprising the steps of:

installing a plurality of piles by boring through the foundations into ground so as to be supportively disposed beneath the pre-existing foundations of the structure to form a first set of vertically installed piles stretching longitudinally of the foundations and with a predetermined number thereof being installed at angles to one another, and a second set of piles installed obliquely to said first set in a non-vertical direction, and stretching longitudinally of the foundations;

injecting concrete material at selected positions between the driven piles to form hardened nodes within the ground connecting at least respective ones of the piles together at said selected positions whereby a trussed grid-structure comprising an array of interconnected rigid triangular structural portions, is developed throughout said plurality of piles to form said pile support arrangement which is capable of absorbing vertical and oblique forces applied thereto and transmitting same to ground, in which the step of injecting concrete material is selected at positions within the driven piles to form rigid triangular pile structures in the direction of continuous footings.

2. A method in accordance with claim 1, wherein the step of driving the piles and selecting the positions of injection of the concrete material is carried out so that rigid triangular pile structures are formed extending in the direction perpendicular to the longitudinal direction of continuous footings.

3. A method in accordance with claim 1, further comprising the step of boring tension anchors horizontally or obliquely towards the rear of said support arrangement and underneath the structure, earth adjacent to the anchor ends being consolidated by injecting concrete material thereto.

4. A method in accordance with claim 3, comprising producing continuous strips, serving as nodal connections, by injecting concrete, the strips serving to distribute a load of earth or superstructure on the piles.

5. A method in accordance with claim 4, in which the nodal connections connected by strips comprise rearwardly extending oblique tension anchors, which engage the strips, connecting the nodal points, between the piles.

6. A method in accordance with claim 5, in which adjacent to the positions of injection at least two washing lances are inserted and earth adjacent to the positions of injection is loosened by at least one lance and thereafter removed by another washing lance and the thus produced cavity is pressed with mortar.

7. A method in accordance with claim 2, further comprising the step of boring tension anchors horizontally or obliquely towards the rear of said support arrangement and underneath the structure, earth adjagage the strips, connecting the nodal points, between the piles.

10. A method in accordance with claim 9, in which adjacent to the positions of injection at least two washing lances are inserted and earth adjacent to the positions of injection is loosened by at least one lance and thereafter removed by another washing lance and the thus produced cavity is pressed with mortar. 

1. A method of production of a pile support arrangement for underpinning the pre-existing foundation of a building structure and the like, comprising the steps of: installing a plurality of piles by boring through the foundations into ground so as to be supportively disposed beneath the pre-existing foundations of the structure to form a first set of vertically installed piles stretching longitudinally of the foundations and with a predetermined number thereof being installed at angles to one another, and a second set of piles installed obliquely to said first set in a non-vertical direction, and stretching longitudinally of the foundations; injecting concrete material at selected positions between the driven piles to form hardened nodes within the ground connecting at least respective ones of the piles together at said selected positions whereby a trussed grid-structure comprising an array of interconnected rigid triangular structural portions, is developed throughout said plurality of piles to form said pile support arrangement which is capable of absorbing vertical and oblique forces applied Thereto and transmitting same to ground, in which the step of injecting concrete material is selected at positions within the driven piles to form rigid triangular pile structures in the direction of continuous footings.
 2. A method in accordance with claim 1, wherein the step of driving the piles and selecting the positions of injection of the concrete material is carried out so that rigid triangular pile structures are formed extending in the direction perpendicular to the longitudinal direction of continuous footings.
 3. A method in accordance with claim 1, further comprising the step of boring tension anchors horizontally or obliquely towards the rear of said support arrangement and underneath the structure, earth adjacent to the anchor ends being consolidated by injecting concrete material thereto.
 4. A method in accordance with claim 3, comprising producing continuous strips, serving as nodal connections, by injecting concrete, the strips serving to distribute a load of earth or superstructure on the piles.
 5. A method in accordance with claim 4, in which the nodal connections connected by strips comprise rearwardly extending oblique tension anchors, which engage the strips, connecting the nodal points, between the piles.
 6. A method in accordance with claim 5, in which adjacent to the positions of injection at least two washing lances are inserted and earth adjacent to the positions of injection is loosened by at least one lance and thereafter removed by another washing lance and the thus produced cavity is pressed with mortar.
 7. A method in accordance with claim 2, further comprising the step of boring tension anchors horizontally or obliquely towards the rear of said support arrangement and underneath the structure, earth adjacent to the anchor ends being consolidated by injecting concrete material thereto.
 8. A method in accordance with claim 7, comprising producing continuous strips, serving as nodal connections, by injecting concrete, the strips serving to distribute a load of earth or superstructure on the piles.
 9. A method in accordance with claim 8, in which the nodal connections connected by strips comprise rearwardly extending oblique tension anchors, which engage the strips, connecting the nodal points, between the piles.
 10. A method in accordance with claim 9, in which adjacent to the positions of injection at least two washing lances are inserted and earth adjacent to the positions of injection is loosened by at least one lance and thereafter removed by another washing lance and the thus produced cavity is pressed with mortar. 